[Fontconfig] Marking glyphs as deliberately blank, per font

[Nicolas Mailhot]

Le Mer 25 novembre 2009 23:54, Behdad Esfahbod a écrit :
>
> On 11/25/2009 07:01 AM, Paul Flo Williams wrote:

>> 2. The fonts.conf page says that 'fonts often include "broken" glyphs which
>>     appear in the encoding but are drawn as blanks on the screen.' A trawl
>> of
>>     the mailing list suggests that this configuration option is ancient --
>> at
>>     least I can't find any discussion of its introduction -- so is this form
>>     of breakage common in fonts we use today?
>
> Donno.

I don't know if it's common, but it definitely exists today. We've seen it
just a few months ago in Fedora (in smc fonts IIRC). In their case it was not
even a blank but a buggy glyph meant to indicate 'reserved'

IMHO now there are efforts in big apps such as Firefox to do more CSS3,
including the CSS3 "select unicode subrange in font" operator, it is becoming
even more urgent for fontconfig to stop considering a font is a basic atomic
unit, and allow fontconfig users to write rules that only apply to part of a
font. It is a huge problem if the font selection model used by fontconfig does
not permit direct mapping from the font selection model used by web-oriented
apps (which can be basically any app now more and more GUI toolkits move to
use of CSS to specify styling)

http://people.mozilla.org/~jdaggett/AdvancingWebTypography.pdf page 42

The "fonts should only include one script with consistent quality so
fontconfig does not need to split them" is a lost cause now, the font
community chose, and not the way fontconfig authors wished.

All the conflicts between scripts and weird inverted logic overrides almost no
one really understands are caused by the "font is an atomic fontconfig unit"
postulate. All past attempts to mitigate those problems without changing the
"font is an atomic fontconfig unit" postulate have failed miserably. Humans
just do not think fonts are an atomic unit, and can not wrap their minds
around a system where they are forced to think this way.

-- 
Nicolas Mailhot